The vision is the most direct and important way for human to observe and recognize our world. We are living in a three-dimensional world, and the human vision can not only perceive the brightness, color, texture information and movement on the surface of an object, but also distinguish its shape, space and spatial position (depth and distance). Currently, the difficulty in researching the machine vision system is how to get the high-precision 3D depth information in real time and improve the intelligent level of the machine.
In the field of industry, the depth perception technology and devices can provide high-resolution and high-precision 3D depth information, which is widely demanded in automotive safety driving assisting, high-speed machine tool processing, industrial modeling, 3D printing, medical imaging and 3D visual perception in the IOT (Internet of Things). In the field of consumer electronics, the depth perception technology and devices can help to improve the intelligent level and interaction ability of electronic products to bring brand-new man-machine interaction for the users' experience and achieve innovative applications in the smart TV, smart phones, household appliances, and tablet PC, etc.
The depth perception technologies can be roughly divided into passive and active solutions. The traditional binocular stereoscopic vision ranging is a passive ranging method, seriously subject to the impact of the ambient light and featuring a complex stereo matching process. The active ranging method is mainly divided into structured light coding and ToF. Therein, the active visual mode based on structured light coding can get image depth information more accurately, is not affected by the ambient light and features a simple stereo matching process, for example, the somatosensory interaction devices of Microsoft Kinect, the patent for invention of “Depth Perception Device and System” newly applied by Apple Co. in 2013, and the depth photographic device released by Intel in 2014, all of them can actively emit the laser pattern to calculate the depth distance. The depth perception devices currently developed by Microsoft, Apple and Intel all adopt the receiving mode by a single camera, so they are mainly suitable for the consumer electronics but can not satisfy the requirements for automobile auxiliary security, industries, 3D printing and other relevant fields in such aspects as depth image resolution, precision and scope of applications. In the same, the stereo matching calculation process is seriously subject to the influence of such factors as illumination, textures and shelters, and it has more errors, larger amount of calculation and more difficulty in generating real-time depth images.